1. Field of the Invention
The present invention relates to a corneal surgical apparatus for incising the cornea of an eye of a patient in a layered fashion at the time of a keratorefrative surgery or the like.
2. Description of the Related Art
In recent years, attention has been focused on a LASIK surgery (laser in situ keratomileusis) for the keratorefractive surgery wherein a flap is formed by incising a corneal portion with a thickness of about 0.15 mm from the corneal epithelium to the corneal stroma with a part of the cornea remaining connected like a hinge, ablating the corneal stroma in a refractive correction amount by an excimer laser light, and returning the flap to its original position. In the LASIK surgery, a corneal surgical apparatus called a microkeratome is used for incising the cornea in a layered fashion.
As a corneal surgical apparatus, one comprising a suction ring to be vacuum-fixed to the conjunctiva surrounding the cornea, a cornea applanating plate for applanating the cornea flatly, and a blade movable toward the hinge while oscillating laterally so as to incise the flattened cornea into a layer with a substantially uniform thickness, is known.
When the suction ring is vacuum-fixed to a patient""s eye prior to flap formation, the ocular pressure (ocular tension) of the patient""s eye is increased in a manner which varies from patient to patient. Further, since suction pressure (vacuum pressure) applied to a space between the patient""s eye and the suction ring is constant, the thickness of the flap varies depending on the ocular pressure. In general, as the ocular pressure is higher, the flap is thicker. If the flap is too thick, corneal weakening or xe2x80x9cEctasiaxe2x80x9d, i.e. where due to weakening the cornea progressively changes over time, is likely to appears. On the other hand, if the ocular pressure is too low, a thin flap or a button hole may be formed through the flap, which hinders the formation of an appropriate flap.
Consistent with the present invention, a corneal surgical apparatus is provided that avoids problems associated with prior corneal surgical apparatuses as discussed herein above.
In one aspect, a corneal surgical apparatus comprises a suction ring to be mounted on a patient""s eye, a suction unit which applies a suction pressure to a space defined between the patient""s eye and the mounted suction ring, a setting unit which sets a desired ocular pressure for the patient""s eye, an input unit which inputs a measured ocular pressure of the patient""s eye, and a controller which controls the suction pressure to be applied by the suction unit based on comparison between the inputted ocular pressure and the set ocular pressure.
In another aspect, a corneal surgical apparatus comprises a suction ring to be mounted on a patient""s eye, a suction unit which applies a suction pressure to a space defined between the patient""s eye and the mounted suction ring, a setting unit which sets a desired ocular pressure for the patient""s eye, an input unit which inputs a measured ocular pressure of the patient""s eye, a pressure sensor which detects the suction pressure applied by the suction unit, a memory which stores the suction pressure detected when the inputted ocular pressure is identical to the set ocular pressure, and a controller which controls the suction pressure to be applied by the suction unit based on comparison between detected suction pressure and the stored suction pressure.
In yet another aspect, a corneal surgical apparatus comprises a suction ring to be mounted on a patient""s eye, a suction unit which applies a suction pressure to a space defined between the patient""s eye and the mounted suction ring, a setting unit which sets a desired ocular pressure for the patient""s eye, an input unit which inputs a measured ocular pressure of the patient""s eye, a pressure sensor which detects the suction pressure applied by the suction unit, a memory which stores a plurality of the inputted ocular pressures measured when different suction pressures are applied, and the detected suction pressures when those ocular pressures are respectively measured, in relation to each other, and a controller which calculates the suction pressure corresponding to the set ocular pressure based on plural sets of the ocular pressures and suction pressures stored in the memory, stores the calculated suction pressure in the memory, and controls the suction pressure to be applied by the suction unit based on comparison between detected suction pressure and the calculated and stored suction pressure.
Both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed.